1. Field of the Invention
The present invention relates to brushless motors installed in, for example, business machines, and in particular, relates to inner-rotor brushless motors including rotors that rotate inside the motors.
2. Description of the Related Art
Inner-rotor DC brushless motors are used for business machines such as laser printers and copiers. Since such an inner-rotor DC brushless motor includes a rotor that rotates inside a stator core, the inertia of the rotor is small compared with that of an outer-rotor motor due to the small rotor diameter, resulting in high controllability. Japanese Patent Laid-Open No. 03-235629 describes an example of an inner-rotor DC brushless motor.
FIG. 16 is a cross-sectional view of a motor described in Japanese Patent Laid-Open No. 03-235629. This motor includes a stator core 1A, stator coils 2 wound around the stator core 1A, a rotor 3 disposed inside the stator core 1A, a frame (outer cylinder) 4A formed of a mild steel sheet into which the stator core 1A is press-fitted such that the outer circumferential surface thereof is brought into close contact with the frame 4A, and a front bracket 5 fitted with the opening of the frame 4A. The frame 4A and the front bracket 5 are fixed by bolts 6.
In this manner, the stator core 1A described in Japanese Patent Laid-Open No. 03-235629 is held by press-fitting the stator core 1A into the frame 4A and by fitting the frame 4A with the front bracket 5.
Since the stator core 1A in the motor described in Japanese Patent Laid-Open No. 03-235629 is held on the premises that the stator core 1A is press-fitted into the frame 4A and the frame 4A is fitted with the front bracket 5 as described above, a reduction in the number of parts, i.e., a further reduction in costs on this regard is demanded.